The purpose of the proposed study is to examine the role of social stimuli in coordinating reproductive functions in rodents. This goal is approached in two ways. First by examining the role of social stimuli on the development of sexual maturity and second by examining the role of social stimuli in modifying the adult reproductive state. A social stimulus in the form of a male pheromone markedly accelerates female sexual maturation in mice. This pheromone occurs in a proteinaceous fraction of male urine and additional research is necessary to isolate the substance in pure form. Such purification will (a) yield the first mammalian priming pheromone, (b) permit detailed studies of its physiological and behavioral effects, and (c) provide a tool for examining the physiological basis of puberty. Studies on reproductive activity in adults will examine the female stimuli to which male hamsters respond and the time course of their endocrine and behavioral response to such stimuli.